Mineral material powder with high dispersion ability and use of said mineral material powder

ABSTRACT

The present invention refers to a mineral matter powder preparation by wet process without acrylic additive or other grinding aid additives and to the use of said mineral matter after an optional hydrophobic treatment. Said mineral material having superior dispersing properties.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national phase of PCT Application No.PCT/EP2013/052940, filed Feb. 14, 2013, which claims priority toEuropean Application No. 12156090.8, filed Feb. 17, 2012 and U.S.Provisional Application No. 61/601,677, filed Feb. 22, 2012.

The present invention refers to a mineral material powder preparation bywet process without acrylic additive or other grinding aid additives andto the use of said mineral material after an optional hydrophobictreatment. Said mineral material having superior dispersing properties.

The present invention further refers to the use of such processedmineral material as mineral filler, and in particular as mineral fillerin paper, paint, coatings, thermoplastic or thermoset resins, rubbers,food, food packaging, cosmetics, pharmaceuticals, and concrete ormortars.

The invention in particular concerns the manufacture of plastics and inparticular thermoplastic resins such as polyolefin, or PVC resins. Todaypart of the costly resins are replaced regularly with less expensivefillers and/or pigments materials in order to reduce costs, while at thesame time trying to improve mechanical and/or optical properties of theunfilled material.

The amounts of fillers present in thermoplastic polymers such aspolyolefins are generally in the range from about 0.1% by weight toabout 70% by weight, whereas in thermoplastic resins such as variousPVC's the fillers are present in amounts from about 1 phr to about 200phr. In particular applications the filler can reach even 400 phr e.g.in cable bedding. Phr has the meaning of parts per hundred resins interm of weight. Such amounts generally allow for a normal processing ofthe thermoplastic polymers.

Said fillers are frequently selected from natural or synthetic calciumcarbonate, dolomites, magnesium hydroxide, kaolin, talc, gypsum ortitanium oxide, and are incorporated in the polymer matrix directly, inthe form of a compound, a dry blend, a masterbatch, or granulates.

However, fine powders, prepared by the methods known in the artcomprising dispersing agents, have a strong tendency to formagglomerates after drying. Such agglomerates make them difficult to bewell dispersed in final mixtures such as polymer matrices, paints,coatings or mortars. To overcome such dispersing problems, the dried andagglomerated particles are frequently submitted to a de-agglomerationstep in order to break up said agglomerates and to promote dispersion.However, said de-agglomeration step is not always sufficient enough andtherefore also dispersion of such material is not satisfactory, leadingto deficiencies and unwanted effects in the final products.

Frequently mineral material is mixed with dispersing agents in order toallow for wet grinding at high solids contents. Current prior art triesto provide solutions to overcome the problem of agglomerates. Finemineral materials are made into masterbatches for easier dosage andbetter dispersion into the polymer matrix. In some applications themineral filler are optionally surface treated.

WO 00/20336 refers to an ultrafine natural calcium carbonate, optionallytreated with one or several fatty acids or one or several salts ormixtures thereof, and its use as a rheology regulator for polymercompositions. The specific surface area is 14 m²/g to 30 m²/g measuredaccording to the BET method to ISO Standard 4652.

WO 03/066692 refers to a binding agent used in a masterbatch to allowre-dispersion of mineral material in thermoplastic resins.

WO 2005/075353 refers to a natural particulate carbonate, wherein thedispersant employed during wet grinding is minimized or removed at alater stage by washing, and subsequent dewatering leads to a productwith reduced surface moisture content at around 0.2 wt %. Remainders ofdispersant chemicals are not greater than 0.05 wt % based on the dryweight of the carbonate. Where the carbonate is to be surface coatedwith a hydrophobising surface treatment agent, a second heating step isused; the second heating step may be applied before and/or during thesurface treatment step. Surface treatment agents may comprise analiphatic carboxylic acid.

WO 2010/030579 refers to stearic acid treated calcium carbonate havinglow or no detectable free stearic acid. The method for treating calciumcarbonate includes the combination of calcium carbonate, water andstearic acid, wherein the amount of water is at least 0.1% by weightrelative to the total weight.

US 2004/097616 refers to a treated particulate calcium carbonate. Saidtreatment being carried out in two steps. The first treatment(pre-treatment) step comprises treatment with at least onepolydialkylsiloxane and a second step comprising a treatment by at leastone fatty acid containing more than 10 carbon atoms, the two steps beingable to be carried out simultaneously.

Facing the dispersing problems, the inventors have surprisingly foundthat preparing a ground mineral material without the use of anydispersants all along the process allows solving the dispersing problemsin final compositions.

The present invention is therefore aimed at a ground natural mineralmaterial and at a process for the preparation of said ground naturalmineral material with good dispersing ability, and with a solid contentof said mineral material of up to about 99.8 wt %, prepared in a wetprocess without acrylic additives or polyphosphates or other grindingaid additives, such acrylic additives or other grinding aid additivesbeing known to the skilled person from the prior art such as WO03/066692, or EP-A-0380430.

A further aspect of the present invention is to provide for a groundnatural mineral material with good dispersing ability in thermoplasticresins such as polyolefins or PVC resins, polyesters, acrylic resins,polyurethane resins, or thermoset resins such as polyurethane foams,(e.g. flexible polyurethane foam), rubbers, unsaturated polyesters, orvulcanized rubbers.

A further aspect of the present invention is directed to a thermoplasticpolymer product comprising the mineral material of the presentinvention.

Another aspect of the present invention is directed to a thermosetpolymer product comprising the mineral material of the presentinvention.

A still further aspect of the present invention is directed to the useof the mineral material of the present invention in thermoplastic resinssuch as polyolefins, styrenic resins, acrylic resins, polycarbonateresins, polyester resins, polyurethane resins, polyamide resins,halogenated polymer resins and combinations thereof.

In yet another aspect of the present invention the halogenated polymerresin is preferably selected from the group comprising PVC,post-chlorinated vinyl polychloride PVCC, vinylidene polyfluoride PVDFor mixtures thereof.

A still further aspect of the present invention is directed to athermoplastic PVC product, wherein the mineral material of the presentinvention is present in amounts from about 1 phr to 200 phr, preferablyfrom about 5 phr to about 19 phr, still more preferably from about 6 phrto about 18 phr, and still more preferably from about 7 phr to about 17phr, and wherein the thermoplastic PVC product has a charpy impactstrength of from 10 kJ/m2 to about 140 kJ/m2, measured according to ISO179/1eA on extruded samples. Further the thermoplastic PVC product hasas gloss 60° [−] from about 20 to about 60, preferably from about 40 toabout 60, still more preferably from about 42 to 55.

A still further aspect of the present invention is directed to the useof the mineral product of the present invention as well as inintermediate and/or final products made of such thermoplastic polymerproduct or thermoset material.

Such thermoplastic polymer product comprising the mineral material ofthe present invention comprise at least one thermoplastic polymerselected from the group comprising polyolefins, styrenic resins, acrylicresins, polycarbonate resins, polyester resins, polyurethane resins,polyamide resins, halogenated polymer resins and combinations thereof.

Final thermoplastic polymer products are profiles, such as windowprofiles, pipes, and technical profiles such as cable- or wire conductswall-, ceiling-, or cladding panels, wire insulations; fibers andnon-wovens, cast films, such as breathable films, raffia, bi-orientedpolypropylene film or blown films, such as mono- or multilayer filmsmade form high density polyethylene (HDPE), or linear low densitypolyethylene (LLDPE), or polypropylene (PP) or mixtures thereof. Themixtures referring to mixed layers. However not only final products butalso intermediate products can be prepared. Such intermediate productsencompass products made by processes comprising an extrusion step, suchas injection moulding, blow moulding, or casting and the resultingproducts such as sheets, films or bottles and profiles. It shall beunderstood, that the processes mentioned here are of mere illustrativepurpose and thus shall not be construed as limiting the invention tothese processes.

Intermediate products like masterbatch, compound, dry-blend orgranulates are encompassed by the present invention as well as othertypes of final products such as non-woven fibres, spun laid fibres,mono- or multifilament products.

The invention will now be further described.

Mineral materials are in general mined materials from quarries and tosome extend also prepared by synthetic methods.

Mined mineral material form the quarries are further processed accordingto their final intended use. Basically the mined rocks undergo a firstsize reduction by jaw crushers or the like before entering thesubsequent milling processes. Such milling or grinding processes beinggenerally performed in dry or in wet, and hence also named so, drymilling or grinding or wet milling or grinding such processes beingknown to the skilled person.

In general, relevant processing agents are present during wet grindingin order to improve the viscosity during the wet grinding. Such relevantprocessing agents affecting the viscosity are known to the skilledperson and can be found among organic or inorganic materials, chemicalsor molecules.

The ground mineral material of the present invention is obtained by aprocess comprising the steps of:

-   -   a) Wet grinding the mineral material in at least one grinding        step in aqueous suspension or slurry until the mineral material        has a weight median particle diameter d₅₀ from 0.1 μm to 1.5 μm,        preferably from 0.4 μm to 1.1 μm, more preferably from 0.6 μm to        0.9 μm, and most preferably of 0.8 μm, and wherein in the at        least one grinding step no relevant processing agents are        present.    -   b) Optionally up-concentrating or dewatering the aqueous        suspension or slurry of step b) to achieve a solid content of        between 50% and 70%, preferably between 55% and 65%, and most        preferably of 60% by weight of dry matter, said mineral matter        having weight median particle diameter d₅₀, from 0.1 μm to 1.5        μm, preferably from 0.4 μm to 1.1 μm, more preferably from 0.6        μm to 0.9 μm, and most preferably of 0.8 μm.    -   c) Drying the aqueous suspension or slurrry of step a) or b) to        achieve a mineral matter with a solids content of 99.8%, wherein        no relevant processing agents are present.    -   d) Optionally surface treatment of the product of step c) with        at least one aliphatic carboxylic acid.

However, in certain cases, it might be advisable to perform ade-agglomeration of the product obtained at step d).

Accordingly, the process according to the present invention ischaracterized in that it comprises a step e) of de-agglomeration of theproduct of step d).

The process of the present invention, may still further comprise in stepa) at least one grinding step wherein the solids content is from 10 wt %to 40 wt %, preferably from 20 wt % to 30 wt %, and mandatory step b),wherein in the grinding steps no relevant processing agents are present.

The mineral material to be used in the above mentioned process can beany natural or synthetic calcium carbonate or calcium carbonatecomprising material selected from the group comprising marble, chalk,dolomite, calcite, limestone, magnesium hydroxide, talc, gypsum,titanium oxide or mixtures thereof.

The wet fine grinding of the process described above can be carried outby processes known to the skilled person, such as described in U.S. Pat.Nos. 5,533,678 or 5,873,935.

The optional up-concentration or dewatering step in the processdescribed above is carried out be means know to the skilled person suchas by mechanical- and/or thermal up-concentration and/or combinationsthereof.

Mechanical up-concentration or dewatering can be carried out bycentrifugation or by filter pressing. Thermal up-concentration methodssuch as solvent evaporation by heat or by flash-cooling. Preferably theup-concentration step in the present invention is carried out bycentrifugation.

The drying step in the process described above is carried out by meansknown to the skilled person and can be selected from the group such asatomizing, spray drying, drying in a rotational oven, drying in a pond,jet-drying, fluid bed drying, freeze drying, fluidized spray drying, orother means suitable for this purpose such as fountain nozzle drying,preferably by spray-drying.

The optional surface treatment of the dried mineral matter productresulting from dewatering or drying step can made in pin-mill withpreheated material, in an attritor mill, cell mill, in a speed mixer, ina dry melt coating, in a fluidized bed, or any other device suitable forthis purpose and known to the skilled person.

The optional surface treatment step can be made after the drying step oras an alternative during the drying step, wherein the surface treatmentproduct is added after the drying step, and in the alternative waybefore or during the drying step.

Said optional treatment being carried out with a surface treatmentproduct in amounts from about 0.01 wt % to about 4 wt %, preferably inamount from about 0.02 wt % to about 2 wt %, more preferably in amountsfrom about 0.03 wt % to about 1 wt % of the mineral matter.

Said surface treatment product being at least one aliphatic carboxylicacid selected from the group comprising butanoic acid, pentanoic acid,hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoicacid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid,pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid,nonadecanoic acid, arachidic acid, heneicosylic acid, behenic acid,lignoceric acid, their esters and/or salts and/or mixtures thereof.

Within the meaning of the present invention, the at least one aliphaticcarboxylic acid refers to straight or linear chain, branched chain,saturated, unsaturated or alicyclic organic compounds composed of carbonand hydrogen. Said organic compound further contains a carboxyl groupplaced at the end of the carbon skeleton which in the case of esters isesterified with C1 to C9 alcohols, preferably mono-alcohols selectedfrom the group comprising, methanol, ethanol, propanol, i-propanol,butanol, i-butanol, pentanol, i-pentanol, 1-hexanol, 2-hexanol,i-hexanol, 1-hepantol, 2-heptanol, i-heptanol, 1-octanol, 2-octanol,i-octanol, 1-nonanol, 2-nonanol, i-nonanol and mixtures thereof.

The product thus obtained by the above described process is a mineralmaterial optionally coated with at least one aliphatic carboxylic acidwherein the untreated mineral material has a median particle sizediameter d₅₀ from 0.1 μm to 1.5 μm, preferably from 0.4 μm to 1.1 μm,more preferably from 0.6 μm to 0.9 μm, and most preferably of 0.8 μm.

Said untreated mineral material further having a BET/N₂ specific surfacearea from 3 m²/g to 13 m²/g, preferably from 4 m²/g to 12 m²/g, morepreferably from 5 m²/g to 10 m²/g, still more preferably from 6 m²/g to9 m²/g, and still more preferably from 7 m²/g to 8 m²/g. Said methodbeing described by Brunauer, St., Emmett, P. H., Teller, E. (1938):Adsorption of Gases in Multimolecular Layers, J. Am. Chem. Soc., 60,309.

Further to this, the optionally coated mineral material obtained by theabove described process has a top cut d₉₈ equal or below 6 μm, such asfrom about 5.9 μm to about 1.8 μm, preferably from about 5 μm to about1.8 μm, more preferably from about 4 μm to about 2.5 μm.

The surface area of the mineral material of the present invention coatedwith the at least one aliphatic carboxylic acid refers to the surfacearea of the mineral material which is accessible or exposed to the atleast one aliphatic carboxylic acid applied by coating techniques knowto the skilled person, such as hot fluidised bed spray coating, hot-wetcoating, solvent-assisted coating or self-assembly coating and the like,thereby forming a monolayer of aliphatic carboxylic acid on the surfaceof the mineral material particle. In this regard, it should be notedthat the amount of aliphatic carboxylic acid which is required for fullsaturation of the accessible surface area is defined as a monolayerconcentration. Higher concentrations thus can be chosen as well therebyforming bi-layered of multi-layered structures on the surface of themineral material particle. Such monolayer concentrations can be readilycalculated by skilled person, based on the publication of Papier,Schultz and Turchi (Eur. Polym. J. Vol. 20, No. 12, pp 1155-1158, 1984).

As previously described, one aspect of the present invention is toprovide for a mineral material with good dispersing ability in finalmixtures such as polymer matrices, paints, coatings or mortars.

A further aspect of the present invention is the use of the mineralfiller obtained by the process of the present invention, in paper,paint, coatings, thermoplastic or thermoset resins, rubbers, food, foodpackaging, cosmetics, pharmaceuticals, mortars or concrete.

Further the present invention refers to a process for producing saidmineral material and to the use of said mineral material inthermoplastic resins such as polyolefins or PVC resins or thermosetresins as well as intermediate and/or final products made of suchthermoplastic or thermoset material comprising the mineral material ofthe present invention. And finally the invention refers also to thethermoplastic resins such as polyolefins or PVC resins or thermosetresins comprising said mineral material.

The thermoplastic polymer is further selected from the group comprisingpolyolefines, styrenic resins, acrylic resins, polycarbonate resins,polyamide resins, halogenated polymer resins, bioplastics,bio-degradable polymers, or combinations thereof.

The thermoset resins are chosen from but not limited to flexiblepolyurethane foams and unsaturated polyesters.

If the polymer resin is a halogenated polymer resin, the halogenatedpolymer resin is preferably selected from the group comprising PVC,plasticized PVC, unplasticized PVC, post-chlorinated vinyl polychlorideCPVC, vinylidene polyfluoride PVDF or mixtures thereof.

Before PVC can be made into finished products, it always requiresconversion into a compound or dry blend by incorporation of additivessuch as but not limited to heat stabilizers, UV stabilizers, lubricants,plasticizers, processing aids, impact modifiers, thermal modifiers,fillers, flame retardants, biocides, blowing agents, smoke suppressorsand optionally pigments.

The amount of mineral matter filler in thermoplastic PVC resins is inthe range from about 1 phr to about 200 phr. In thermoplastic PVC windowprofiles the amount of mineral material is in the range from about 1 phrto about 20 phr, preferably from about 5 phr to about 19 phr, still morepreferably from about 6 phr to about 18 phr, and still more preferablyfrom about 7 phr to about 17 phr.

The term “phr” in the meaning of the present invention means “parts perhundred resins”. In particular, if 100 parts of polymer are used, thequantity of other ingredients is expressed in relation to these 100parts of polymer by weight.

The mineral matter filler of the present invention can be present inthermoplastic PVC resins in amounts from or more than 4 phr in respectto the thermoplastic material, preferably in amount of at least 9 phr,of at least 10 phr, of at least 11 phr, of at least 12 phr, of at least13 phr, of at least 14 phr, of at least 15 phr, of at least 16 phr, ofat least 17 phr, of at least 18 phr, or of at least 19 phr, whenincorporated into thermoplastic PVC window profile.

Such thermoplastic PVC resins have the advantage that their mechanicalor optical properties such as processability, gloss and/or impactstrength are hereby not affected or only little, i.e. within thedeviation limits accepted by the industries and/or client.

An important side effect is that due to the replacement of polymer resinin amounts of up to 200 phr, final thermoplastic PVC parts can beproduced more cost efficient. The skilled person thus will easilyrecognize that use of less thermoplastic polymer material in finalproducts will significantly reduce cost of the final products such asprofiles, e.g. window profiles, pipes, technical profiles such as cable-or wire conducts, wall-, ceiling-, or cladding panels, wire insulations,fibres and non-wovens.

However not only final products but also intermediate products can beprepared. Such intermediate products encompass products made byprocesses comprising an extrusion step, such as injection moulding, blowmoulding, or casting and the resulting products such as profiles,sheets, films or bottles. It shall be understood, that the processesmentioned here are of mere illustrative purpose and thus shall not beconstrued as limiting the invention to these processes.

PVC can be further divided into rigid PVC, plasticized PVC andplastisols with their corresponding final products or application. RigidPVC is generally used in profiles, such as such as window profiles,comprising mineral fillers from 1 phr to about 12 phr, in sidings,comprising mineral fillers from 1 phr up to 100 phr, in tubes or pipes,comprising mineral fillers from 1 phr up to 60 phr. Plasticized PVC isgenerally used in flooring, comprising mineral fillers from about 1 phrup to 200 phr, in cable conducts, comprising mineral filler from about 1phr up to 150 phr. Plastisols are generally used in underbody carmaterial, comprising mineral fillers in amounts from about 1 phr to upto 200 phr. Mineral fillers such as CaCO₃, are thus generally employedin amounts from about 1 phr to about 200 phr. In particularapplications, such as profiles e.g. window profiles, this amount isgenerally in the range from about 1 phr to about 20 phr. The amount offiller described above are not fix and the upper limits thus may stillvary up or down by to 10 to 50%.

If the polymer resin is a styrenic resin, the polymer resin ispreferably selected from the group comprising general purposepolystyrene (GPPS), high impact polystyrene (HIPS), styrene-butadienecopolymers, block copolymers of the Kraton™ type, resins of thestyrene-acrylonitrile type, acrylate-butadiene-styrene resins,methylmethacrylate styrene copolymers and mixtures thereof.

If the polymer resin is an acrylic resin, the polymer is preferably amethyl polymethyacrylate.

If the polymer resin is a polyolefin resin, the polyolefin resin ispreferably selected from the group comprising homopolymers and/orcopolymers of polyethylenes (crosslinked or non-crosslinkedpolyethylene) and/or propylenes and/or mixtures thereof. Polyethylenescan be further sub-divided into HDPE, LDPE, LLDPE.

If the polymer is a polyester resin, the polymer resin is preferablyselected from the group comprising polyethylene terephthalate (PET)and/or the polybutylene terephthalate, polycarbonates, as well asthermoplastic resins comprising phthalate esters such as iso-phthalateesters.

Within the context of the present invention bioplastics are a form ofplastics derived from renewable biomass sources such as vegetable fatsand oils, corn, starch, pea starch, or microbiota, rather thanfossile-fuel plastics which are derived from crude oil fractions. Some,but not all bioplastics are designed to biodegrade, such as polylacticacid plastics (PLA), or polyhydroxyalkanoate bioplastics (PHA). Starchbased bioplastics, usually made of amylose or amylosepectin, are oftenblended with biodegradable polyesters. These blends are mainlystarch/polycaprolactone (PCL-blend), or starch/polybutyleneadipate-co-therephthalate. Other bioplastics or biodegradablebioplastics are further described in the literature and/or the Internet.

In a preferred embodiment the thermoplastic resin is selected fromPolyvinylchloride.

Preferably the polyvinylchloride resin comprises a polyvinyl chloridehomopolymer or a copolymer of vinylchloride with a copolymerizableethylenically unsaturated monomer. Depending on the use of the final PVCproducts the appropriate K-value is chosen. The K-value is a measure ofthe molecular weight of PVC based on measurements of viscosity of a PVCsolution. It ranges usually between 35 and 80. Low K-values imply lowmolecular weight (which is easy to process but has inferior properties)and high K-values imply high molecular weight, (which is difficult toprocess, but has outstanding properties).

Polyvinylchloride resins suitable for the use in the present inventionare available from a wide variety of commercial sources. Such aspolyvinylchloride from INEOS Chlor Americas Inc, Shin-Etsu, Vestolit,LVM, Aiscondel, Cires, Solvin, Arkema, or Vinnolit.

In a preferred embodiment, the thermoplastic PVC resin compositioncomprises the mineral matter material of the present invention inamounts of from 4 phr to about 19 phr. The thermoplastic PVC resincomposition may comprise further additives generally used for preparingthe final thermoplastic PVC polymer products such as window profiles.Such additives may be added for the purpose of e.g. increasing impactresistance, melt elasticity, stability and resistance to oxidation ofthe polymer product. The thermoplastic PVC resin composition may furthercomprise at least one of the components selected from the groupcomprising, stabilizers, impact modifiers, lubricating agents,processing aids, pigments and combinations thereof.

In one embodiment the thermoplastic PVC resin composition comprising themineral material of the present invention in amounts from 1 phr to 20phr, further comprises at least one stabilizer. Such stabilisers areknown in the art and are provided from manufacturers such as Baerlocheror Crompton Corp. The stabilizers are typically selected from Pbcontaining stabilizers, Sn containing stabilizers, Ca—Zn containingstabilizers, organic based stabilizer OBS®, Ca-organic basesstabilizers, Ba—Zn containing stabilizers, or combinations thereof.

In one particular embodiment the thermoplastic PVC resin compositioncomprising the mineral material of the present invention in amounts from1 phr to 20 phr, further comprises a Ca—Zn containing stabilizer in anamount of 1 phr to 6 phr, preferably from 2 phr to 5 phr, morepreferably from 3 phr to 4 phr. In particular embodiment the amount ofthe Ca—Zn containing stabilizer is 3.5 phr. Such PVC composition beingused for producing window profiles.

Ca—Zn containing stabilizers suitable for the present invention areavailable from a wide variety of suppliers. Such as Stabilox CZ 2913 GN,from Reagens Deutschland GmbH.

Alternatively or in addition the stabilizer may also be selected fromorgano-tin stabilizers. Such as methyl-tin, reverse ester tins, and tinmercaptides. Such organo-tin stabilizer encompass several classes ofcompounds. Tin mercaptides comprise blends of dialkyl-tinbis(iso-thioglycolates) with monoalkyl-tin tris(iso-thioglycolates).

Other organo-tin stabilizers which may be added comprise dialkyl-tincarboxylate esters, of which the most common are dialky-tin maleateesters such as dialkly-tin maleate octoate.

If an organo-tin stabilizer is added to the thermoplastic PVC resin,said organo-tin stabilizer is preferably added in amounts of 0.5 phr toabout 2 phr.

Additionally or alternatively, further additives such as lubricants,calcium stearate and/or pigments like titanium dioxide may be added, ifnecessary. Such further additives are preferably present in thethermoplastic PVC resin composition comprising the mineral material ofthe present invention in amounts of at least 0.1 phr, preferably inamounts from about 0.01 phr to about 9 phr, preferably from about 0.5phr to about 5 phr.

Lubricants, calcium stearates and/or titanium dioxide suitable for theuse in the present invention, e.g. Tyrin 7000, Paraloid KM366,Durastrenght 340, Realube AIS, Realube 3010, Kronos CL2220, Tiona 168,are available from a variety of suppliers such as Baerlocher, Chemson,Ika, Reagens, Akdeniz Kimya, Kronos, DuPont, Huntsman and many more.Useful lubricants, internal as well as external lubricants, are known inthe art and can be selected from Table 1.

The content of Table 1 is of mere illustrative character and shall notbe construed to be limited to these lubricants.

TABLE 1 Chemical Lubrication name Length of chain Polar moiety internalexternal Fatty alcohol C₁₄-C₁₈ —OH ****** Dicarboxylic C₁₄-C₁₈ —COO—****** acid ester Fatty acid C₁₄-C₁₈ —COO— ***** * glycerol ester Metalsoap C₁₄-C₁₈ —COO—Ca ***** * Fatty acid C₁₆-C₁₈ —COO— and —OH ***** *glycerol ester Fatty acid C₁₄-C₁₈ —COO— **** ** ester Fatty acid C₁₆-C₁₈—COO— **** ** ester Ester wax C₆-C₁₈ —COO— *** *** Ester wax C₁₄-C₁₈—COO— ** **** Fatty acid C₁₄-C₁₈ CO—NH—CO— ** **** amide Metal soap C₁₈—COO—Zn ** **** Hydroxy C₁₄-C₁₈ —COOH and —OH * ***** fatty acids Fattyacid >C₁₄-C₁₈ —COOH * ***** Paraffin wax >C₂₀ Non-polar ******Polyethylene ≈C₁₀₀ Non-polar ****** wax

The present invention is now further explained by way of examples andfigures, which are not intended to limit the scope of the invention inany way.

DESCRIPTION OF THE FIGURES

FIG. 1a shows a SEM picture of an untreated CaCO₃ obtained by theprocesses of the prior art. After drying and before de-agglomeration,large agglomerates still are present and thus provide for a lesshomogeneous dispersion of the CaCO₃ in final products.

FIG. 1b shows a SEM picture which of an untreated CaCO₃ obtained by theprocess of the present invention. After drying and beforede-agglomeration almost no agglomerates are present and thus promotegood dispersing ability of the CaCO₃ in final products

FIG. 2a shows pictures of blown film samples according to table 7,wherein two prior art CaCO3 masterbatches are compared to themasterbatch of the present invention at CaCO3 concentrations of 20 wt %of the whole polymer.

FIG. 2b shows pictures of blown film samples according to table 7,wherein a prior art CaCO3 masterbatch is compared to the masterbatch ofthe present invention at CaCO3 concentrations of 10 wt % of the wholepolymer.

EXAMPLES

Measuring Methods

If not otherwise indicated, the parameters mentioned in the presentinvention are measured according to the measuring methods describedbelow.

Weight Median Particle Diameter d₅₀ Value

Throughout the present invention, d₅₀ is the weight median particlediameter by weight, i.e. representing the particles in such a mannerthat 50 wt-% of the particles are coarser or finer.

The weight median particle diameter was measured according to thesedimentation method. The sedimentation method is an analysis ofsedimentation behaviour in a gravimetric field. The measurement is madewith a Sedigraph™ 5100 from Micromeritics Instrument Corporation. Themethod and the instrument are known to the skilled person and arecommonly used to determine grain size of fillers and pigments routinely.The measurement is carried out in an aqueous solution of 0.1 wt %Na4P2O7. The samples were dispersed using a high speed stirrer andultrasound.

Specific Surface Area (BET)

The specific surface area was measured using nitrogen and the BET methodaccording to ISO 9277.

Charpy Impact Strength

Charpy notched impact strength was measured according to 179-1:2000according to conditions 1fC and 1eA on V-notched extruded samples whichwere cut out of the extrudate in machine direction. Measuringconditions: 23° C.±2° C. and 50%±10% relative humidity. The testspecimens were prepared by extrusion as described in ISO 3167 Typ A.

Moisture Content

Moisture content of the inorganic mineral material is determined bythermogravimetric analysis (TGA). TGA analytical methods provideinformation regarding losses of mass with great accuracy and is commonknowledge, and described in “Principles of Instrumental analysis”, fifthedition, Skoog, Holler, Nieman, 1998 (first Ed. 1992) in Chapter 31,pages 798-800, and in many other commonly known references known to theskilled person. In the present invention, thermogravimetric analysis wasperformed using a Mettler Toledo TGA 851 based on a sample of 500 mg±50mg and a scanning temperature from 105° C. to 400° C. at a rate of 20°C./minute under an air flow of 70 ml/min.

K-Value of PVC: A measure of the molecular weight of PVC based onmeasurements of viscosity of a PVC solution. It ranges usually between35 and 80. Low K-values imply low molecular weight (which is easy toprocess but has inferior properties) and high K-values imply highmolecular weight, (which is difficult to process, but has outstandingproperties). In general, K-values for a particular PVC resin areprovided by the resin producer either on the packaging or theaccompanying technical data sheet.

Brookfield™ Viscosities

The viscosities of the mixtures were measured using a Brookfield™ (modelDV-II+) viscometer at 30° C. with spindle n° 5, at 10 rpm and 100 rpm.

Surface Gloss

The surface gloss was measured with a Byk Spectro Guide Sphere Gloss atan angle of 60° from the plane surface according to ISO 2813:1994. Thegloss value is determined by calculating the average value of nmeasurement. In the present set up n=10.

Test 1:Preparation and Testing of Samples (in Rigid PVC)

TABLE 2 Example C1 C1′ (6 hr)* C2 E1 E2 PVC K-value 66 100 (phr)  100(phr)  100 (phr)  100 (phr)  100 (phr)  (Evipol SH6630) Ca—Zn containingstabilizer 4.3 (phr) 4.3 (phr) 4.3 (phr) 4.3 (phr) 4.3 (phr) (StabiloxCZ 2913 GN) Lubricant: 12-Hydroxy 0.2 (phr) 0.2 (phr) 0.2 (phr) 0.2(phr) 0.2 (phr) stearic acid (Realube AIS) Lubricant: PE wax 0.15 (phr) 0.15 (phr)  0.15 (phr)  0.15 (phr)  0.15 (phr)  (Realube 3010) Titaniumdioxide 3.5 (phr) 3.5 (phr) 3.5 (phr) 3.5 (phr) 3.5 (phr) (Kronos 2220)Acrylic impact modifier   6 (phr)   6 (phr)   6 (phr)   6 (phr)   6(phr) (Durastrength 340) Ground natural CaCO₃   8 (phr)   8 (phr)  16(phr)   8 (phr)  16 (phr) BET [m²/g] 7.9 7.9 7.9 5.9 5.9 Median d₅₀ [μm]0.94 0.94 0.94 0.71 0.71 Top Cut d₉₈ [μm] 5 5 5 3 3 Charpy impactresistance 51 47 42 56 55 [kJ/m²] ISO179/1fC Gloss 60°[—] 36 34 22 49 36L*-value 95.32 95.36 95.48 96.17 96.02 a*/b*-value −0.43/3.43 −0.42/3.41−0.20/3.95 −0.36/3.64 −0.25/4.02 Torque [Nm] 513 505 482 472 461 (6 hr)*C1′ is a reference run after continuous extrusion for 6 hr.

The components for comparative examples C1, C1′, C2 as well as inventiveexamples E1 and E2 in Test 2 were previously mixed using the usualhot/cold mixing process known to the skilled person, and extruded on aGöttfert extrusion line equipped with a Krauss-Maffei plastificationunit, L/D 32, with counter rotating parallel twin screws, the screwshaving a diameter of 30 mm each.

Test 2:Preparation and Testing of Samples

Example C1 C1′ (2 hr)* C2 E1 E2 PVC K-value 65  100 (phr)  100 (phr) 100 (phr)  100 (phr)  100 (phr) (Vestolit P 1982 K) Ca—Zn containing3.95 (phr) 3.95 (phr) 3.95 (phr) 3.95 (phr) 3.95 (phr) stabilizer fromBarlocher Calcium stearate  0.2 (phr)  0.2 (phr)  0.2 (phr)  0.2 (phr) 0.2 (phr) Lubricant: PE wax 0.15 (phr) 0.15 (phr) 0.15 (phr) 0.15 (phr)0.15 (phr) (Realube 3010) Titanium dioxide  3.5 (phr)  3.5 (phr)  3.5(phr)  3.5 (phr)  3.5 (phr) (Kronos 2220) Ground natural CaCO₃   8 (phr)  8 (phr)   16 (phr)   8 (phr)   16 (phr) BET [m²/g] 7.9 7.9 7.9 5.9 5.9Median d₅₀ [μm] 0.94 0.94 0.94 0.71 0.71 Top Cut d₉₈ [μm] 5 5 5 3 3Charpy impact resistance 55 39 49 130 118 [kJ/m²] ISO179/1eA Gloss60°[—] 42 43 27 56 47 L*-value 95.23 95.22 96.17 96.82 95.99 a*/b*-value−0.40/3.38 −0.42/3.25 −0.52/3.70 −0.39/3.09 −0.24/3.86 Torque [Nm] 515520 511 490 475 (2 hr)* C1′ is a reference run after continuousextrusion for 2 hr.

The components for comparative examples C1, C1′, C2 as well as inventiveexamples E1 and E2 in Test 1 were previously mixed using the usualhot/cold mixing process known to the skilled person, and extruded on aKrauss-Maffei KMD 2-90 profile extrusion line, L/D 22, with counterrotating parallel twin screws, the screws having a diameter of 90 mmeach.

The CaCO₃ of comparative examples C1, C1′ and C2, is a prior art CaCO₃having the following characteristics. The CaCO₃ is of natural origin.The BET surface area is 7.9 m²/g with a mean particle diameter d₅₀ of0.94 μm. The CaCO₃ was prepared according to grinding methods known tothe skilled person and as described in U.S. Pat. Nos. 5,533,678 or5,873,935 with the use of dispersing agents during the wet grindingprocess and treated with 1 wt % of an industrial fatty acid mixture ofC₁₈/C₁₆ in amounts of 50 wt %/50 wt %. Such industrial fatty acidmixtures can vary in their C₁₈/C₁₆ amount from about 30 wt %-70 wt %/70wt %-30 wt %, as well as in their carbon chain length being from C₁₄ toC₂₀.

The CaCO₃ of the inventive examples E1 and E2 have been preparedaccording to the process of the present invention, thus without relevantprocessing aids during wet grinding, and with a surface treatment afterdrying with 1 wt % of an industrial fatty acid mixture of C₁₈/C₁₆ inamounts of 50 wt %/50 wt %.

Test 1

E1 provides for a 10% increase in charpy impact resistance (ISO 179/1fC)with same amount (8 phr) of CaCO₃ of the present invention as thecomparative example C1. With higher amount E2 (16 phr) of the CaCO₃ ofthe present invention the charpy impact strength (ISO 179/1fC) on anextruded profile is still about 10% higher than the charpy impactstrength of C1 or C1′ and even 20% than comparative example C2 with sameamounts of CaCO₃ of 16 phr. A further change can be observed in thetorque of the extruder, which is affected positively, as the Torque isdecreasing with increasing CaCO₃ content provided according to thepresent invention. Lower torque means lower energy consumption in firstplace but also less stress imposed on the polymer matrix duringextrusion.

Gloss 60° [−] of E1 (8 phr), and E2 (16 phr) is significantly improvedover comparative examples C1 (8 phr) and C2 (16 phr) by about 35% at 8phr and by about 60% at 16 phr. Further optical properties such asbrightness—see L*—value, are not affected to the negative andred—/yellowness—values—see a*/b*—values, remain within the tolerancesand thus the overall benefit provided by the present invention is shown.Noteworthy that a thermoplastic PVC resin comprising a mineral filler ofthe present invention has improved gloss and Charpy impact strength aswell as a better processability as lower torque is needed when made intoa final product such as window profile.

Test 2

E1 provides for an increase in the Charpy impact resistance (ISO179/1eA)by about 100%, with same amount (8 phr) of CaCO₃ of the presentinvention as the comparative example C1. With higher amount (16 phr) ofthe CaCO₃ of the present invention the Charpy impact strength(ISO179/1eA) on an extruded profile is still over 100% higher than theCharpy impact strength of C1, C1′ and C2. A further change can beobserved in the torque of the extruder, which is affected positively, asthe Torque is decreasing with increasing CaCO₃ content providedaccording to the present invention. Lower torque means lower energyconsumption in first place but also less stress imposed on the polymermatrix during extrusion. Finally optical properties such as gloss oryellowness are within the tolerances and thus the overall benefitprovided by the present invention is show, noteworthy the replacement ofat least 8 phr of a PVC polymer by a filler without negatively affectingphysical and optical properties.

Gloss 60° [−] of E1 (8 phr), and E2 (16 phr) is significantly improvedover comparative examples C1 (8 phr) and C2 (16 phr) by about 30% at 8phr and by about 10% at 16 phr. Further optical properties such asbrightness—see L*—value, are not affected to the negative andred-/yellowness—values—see a*/b*—values, remain within the tolerancesand thus the overall benefit provided by the present invention is shown.Noteworthy that a thermoplastic PVC resin comprising a mineral filler ofthe present invention has improved gloss and Charpy impact strength aswell as a better processability as lower torque is needed when made intoa final product such as window profile.

The thermoplastic PVC polymer product comprising the thermoplastic PVCresin composition comprising the mineral material of the presentinvention in amounts from 1 phr to 20 phr, preferably from about 5 phrto about 19 phr, still more preferably from about 6 phr to about 18 phr,and still more preferably from about 7 phr to about 17 phr, and furthercomprising additives such as stabilizers, impact modifiers, lubricatingagents, processing aids, pigments and combinations thereof in amounts aspreviously described has a charpy impact strength at 23° C. of from 80kJ/m² to 150 kJ/m², preferably from 100 kJ/m² to 140 kJ/m² measuredaccording to ISO 179/1eA on extruded samples.

The thermoplastic PVC polymer product comprising the thermoplastic PVCresin composition comprising the mineral material of the presentinvention in amounts from 1 phr to 20 phr, preferably from about 5 phrto about 19 phr, still more preferably from about 6 phr to about 18 phr,and still more preferably from about 7 phr to about 17 phr, and furthercomprising additives such as stabilizers, impact modifiers, lubricatingagents, processing aids, pigments and combinations thereof in amounts aspreviously described has a Charpy impact strength at 23° C. of from 50kJ/m² to 80 kJ/m², preferably from 50 kJ/m² to 70 kJ/m² measuredaccording to ISO 179/1fC on extruded samples.

The term “charpy impact strength” within the meaning of the presentinvention refers to the kinetic energy per unit area required to break atest specimen under flexural impact. Test specimen is held as a simplysupported beam and is impacted by a swinging pendulum. The energy lostby the pendulum is equated with the energy absorbed by the testspecimen.

Further embodiments comprising the mineral matter according to thepresent invention are now presented.

Use in Unsaturated Polyester Resins

The mineral material of the present invention is made into unsaturatedpolyester resins in order to provide for a sheet moulding compound (SMC)or bulk moulding compound (BMC) which is a mould fibre-reinforcedpolyester material primarily used in compression moulding. Themanufacturing of SMCs require in general two steps. The first stepconsists of providing for a thermoset resin, the second step (conversionoperation), known as SMC compression, is the moulding in a hot press.During said conversion operation the combined action of increasedtemperature and mechanical pressure allows the filling of the mould withthe SMC and the crosslinking of the thermoset resin.

An unsaturated polyester resins comprising chopped glass fibres with 2-3cm length and around 100 μm in diameter is mixed with the mineralmaterial of the present invention, to provide for a sheet like, ductile,non-sticky SMC. The quality of the filled thermoset resin mainly dependson the contact between the glass fibres and the filled unsaturatedpolyester resin, which is strongly affected by the rheology of thecomposition, and therefore depending on a good dispersing ability of themineral filler of the present invention.

Said mineral material according to the present invention, is preferablyan untreated CaCO₃ with a median particle size diameter of about 0.1 μmto about 1.5 μm, preferably from about 0.4 μm to about 1.1 μm, morepreferably from about 0.6 μm to about 0.9 μm, and most preferably of 0.8μm, and wherein the BET/N₂ specific surface area is measured on theuntreated mineral material and amounts from 3 m²/g to 13 m²/g,preferably from 6 m²/g to 10 m²/g, more preferably from 7 m²/g to 8m²/g.

The mineral material according to the present invention has a top cutd₉₈ equal or below 6 μm, such as from about 5.9 μm to about 1.8 μm,preferably from about 5 μm to about 1.8 μm, more preferably from about 4μm to about 2.5 μm

The amount of the CaCO₃ according to the present invention used is fromabout 10 wt % to about 75 wt %, preferably from about 15 wt % to about60 wt %, more preferably from about 20 wt % to about 50 wt %. The amountof glass fibres is comprised from about 5 wt % to about 45 wt %,preferably from about 10 wt % to about 40 wt %, more preferably fromabout 15 wt % to about 35 wt %. The unsaturated polyester resin amountsfrom about 5 wt % to about 35 wt %, preferably from about 10 wt % toabout 30 wt %, more preferably from about 10 wt % to about 20 wt %.

The SMC may further comprise other compounds in usual amounts such asadditives to prevent shrinkage, flame retardants, crosslinking promoterssuch as peroxides, colorants, pigments, electro conducting materials andmany more.

According to one embodiment, 75 kg of an unsaturated polyester resin(Palapreg P18-03, from DSM), 50 kg of low profile additive (Parapleg H852-03, from DSM) and 250 kg of an untreated CaCO₃ according to thepresent invention were mixed, wherein the CaCO₃ had a mean particle sized₅₀ of 1.5 μm, a top cut d₉₈ of 6 μm and BET specific surface area of3.8 m²/g. Brookfield™ viscosities of the formulation were measured after2 hrs at 30° C., at 10 rpm (revolutions per minute) and 100 rpm, usingspindle no 5, and are summarized in Table 3.

TABLE 3 Brookfield Brookfield viscosity at 10 rpm, viscosity at 100 rpm,30° C. (mPa · s) 30° C. (mPa · s) Brookfield viscosities 31′120 14′500(spindle n^(o)5) of the formulation after 2 hrs

Brookfield™ viscosities of the filled unsaturated polyester resin,comprising the CaCO₃ of the present invention, showed a very goodquality of the paste resulting in a good wetting effect of the glassfibers by the unsaturated polyester paste. The SMC and BMC obtainedafter molding with said glass fiber filled unsaturated polyester resinprovided for a high surface quality and good mechanical properties.

Use in Flexible Polyurethane Foam

The mineral material of the present invention is made into flexiblepolyurethane foam.

In general polyurethane foams are prepared by methods comprising thesteps of reacting a polyol with an isocyanate in the presence of waterto form a flexible polyurethane foam. The polyol include polyetherpolyols, obtained, for example by adding propylene oxide or ethyleneoxide to glycerine, trimethlyolpropane or diethylene glycol, althoughthe type of the base polyol is not critical. The polyol preferably has aon OH value of 10 to 100, preferably from 20 to 80, more preferably from30 to 55.

In order to get a good dispersed mineral material according to thepresent invention in the flexible polyurethane foam, the mineralmaterial of the present invention is introduced into the polyol matrix,prior to mixing with the other components.

The mineral material to be used in the above mentioned process can beany natural or synthetic calcium carbonate or calcium carbonatecomprising material selected from the group comprising marble, chalk,dolomite, calcite, limestone, magnesium hydroxide, talc, gypsum,titanium oxide or mixtures thereof.

Said mineral material according to the present invention, is preferablyan untreated CaCO₃ with a median particle size diameter of about 0.1 μmto about 1.5 μm, preferably from about 0.4 μm to about 1.1 μm, morepreferably from about 0.6 μm to about 0.9 μm, and most preferably of 0.8μm, and wherein the BET/N₂ specific surface area is measured on theuntreated mineral material and amounts from 3 m²/g to 13 m²/g,preferably from 4 m²/g to 12 m²/g, more preferably from 5 m²/g to 10m²/g, still more preferably from 6 m²/g to 9 m²/g, and still morepreferably from 7 m²/g to 8 m²/g. Said untreated mineral materialobtained by the process of the present invention has a top cut d₉₈ equalor below 6 μm, such as from about 5.9 μm to about 1.8 μm, preferablyfrom about 5 μm to about 1.8 μm, more preferably from about 4 μm toabout 2.5 μm.

The amount of the CaCO₃ according to the present invention used is fromabout 10 wt % to about 75 wt %, preferably from about 15 wt % to about60 wt %, more preferably from about 20 wt % to about 45 wt %.

According to one embodiment, flexible polyurethane foam was prepared bymixing the components as presented in Table 4.

TABLE 4 Unit Formulation Polyol I OH = 48 parts 100 CaCO₃ according tothe present invention % of polyol 10 Triethylene diamine diluted at 33%(w/w) % of polyol 0.15 in dipropylene glycol Stannous octoate % ofpolyol 0.22 Tegostab BF 2370 from Evonik % of polyol 0.8 Water % ofpolyol 4.6 Toluene diisocyante (TDI) 80% % of polyol 56.2 Isocyanateindex % 108 Cream time s 18.1 Rise time s 96

The preparation of the flexible polyurethane foam was made according tothe following procedure:

In a sealable glass bottle of 220 ml, toluene di-isocyanate (TDI) wasweighed after storage for a minimum of 6 hours at room temperature.After weighing, the bottle was closed and stored at room temperature.

In a polyethylene bottle of 800 ml, the following ingredients wereweighed in order of citation: the surfactant, polyol, water, aminecatalyst, the tin-based catalyst. It should be noted that all thesereagents were stored at room temperature at least 6 hours beforehandling.

The polyethylene bottle was stirred with a mixer GRENIER-CHARVETequipped with a high shear disk. Stirring was carried out at a speedsufficient to create a vortex.

The TDI previously prepared in the glass bottle was then emptiedcompletely in the polyethylene bottle and a stopwatch was put intooperation simultaneously (the t=0 of the experiment). After 20 secondsof intensive mixing of the reaction medium, the content of thepolyethylene bottle was put promptly and fully into a paper box with aform of cube (side 20 cm). The cream time of the beginning of theexpansion was measured and the corresponding rise time at the end of theexpansion of the flexible polyurethane foam.

After the end of the rise, the polyurethane foam sample thus preparedwas introduced into a ventilated oven at 100° C. for 15 minutes. At theend of the curing, the polyurethane foam sample was stored for at least24 hours before being cut for the measurement of differentphysico-chemical and mechanical properties.

The values given in table 5 are the average of measurements on fivesamples of flexible polyurethane foam.

The tests were performed to obtain between 300 and 500 g of polyurethanefoam. When the calcium carbonate was introduced in the composition ofthe foam, it has been incorporated into the polyethylene bottle afterthe polyol and before the water. Before the introduction into thecomposition the CaCO₃ of the present invention was dispersed in a partof the polyol used in the composition. The concentration of the calciumcarbonate in the polyol was between 40 and 50% by weight.

The CaCO₃ of the present invention used in this example had a meanparticle size d₅₀=1.4 μm, a top cut d₉₈ equal to 5 μm and a BET specificsurface area equal to 5 m²/g.

The viscosity of the dispersion (45 wt % of CaCO₃) was measured with aBrookfield™ viscometer at 23° C. and was equal to 3800 mPa·s.

TABLE 5 Density (kg/m³) 26 Compression to 40% (NFT 56-110) (N/dm²) 50Compression to 50% (NFT 56-110) (N/dm²) 56.8 Tear resistance (NFT56-109) (N/m) 767 Tensile strength (NFT 56-108) (N/mm²) 0.098 Elongationat break (NFT 56-108) (%) 139

Use in LLDPE Masterbatch

The mineral material of the present invention is made into a masterbatchof a polyolefin. In particular the mineral material of the presentinvention in treated form is compounded into a linear low densitypolyethylene (LLDPE). The LLDPE is present in amounts of about 10 wt %to about 80 wt % and the treated mineral material of the presentinvention is present in amounts of about 90 wt % to about 20 wt %.Preferably the LLDPE is present in amount of 20 wt % to about 50 wt %and the treated mineral material according to the present invention ispresent in amounts of 80 wt % to about 50 wt %. More preferably theLLDPE is present in amounts of 25 wt % to about 45 wt % and the treatedmineral material according to the present invention is present inamounts of 85 wt % to about 60 wt %, most preferably the masterbatch iscomposed of 30 wt % to 40 wt % of the LLDPE and of 70 wt % to about 60wt % of the treated mineral material according to the present invention,and wherein the median particle diameter d₅₀ was determined on theuntreated mineral material and has a value from about 0.1 μm to about1.5 μm, preferably from about 0.4 μm to about 1.1 μm, more preferablyfrom about 0.6 μm to about 0.9 μm, and most preferably of 0.8 μm, andwherein the BET/N₂ specific surface area is measured on the untreatedmineral material and amounts from 3 m²/g to 13 m²/g, preferably from 6m²/g to 10 m²/g, more preferably from 7 m²/g to 8 m²/g.

The mineral material can be any natural or synthetic calcium carbonateor calcium carbonate comprising material selected from the groupcomprising marble, chalk, dolomite, calcite, limestone, magnesiumhydroxide, talc, gypsum, titanium oxide or mixtures thereof.

A filter pressure test was performed in order to determine the filterpressure value FPV of a LLDPE masterbatch as described above andcompared to the FPV a masterbatch comprising a mineral material of theprior art. An example of a masterbatch is given in Table 6, wherein 30wt % of an LLDPE was used as carrier resin.

The filter pressure test as herein described provides for the FilterPressure Value, in the present case, of dispersed mineral material in aLLDPE. The Filter Pressure Value FPV is defined as the increase ofpressure per gram filler. This test is performed to determine thedispersion quality and/or presence of excessively coarse particles oragglomerates of mineral materials in a masterbatch. Low Filter PressureValues refers to a good dispersion and fine material, wherein highFilter Pressure Values refer to bad dispersion and coarse oragglomerated material.

The Filter Pressure test was performed on a commercially availableCollin Pressure Filter Test, Teach-Line FT-E20T-IS, according to thestandard EN 13900-5. Filter type used was 14 μm and 25 μm, extrusion wascarried out at 200° C.

The masterbatch which was tested was composed of 30 wt % of a LLDPE fromDow (Dowlex 2035 G), with a density of 0.919 g/cm³, and a MFR_(2.16) at190° C. was 6.0 g/10 min, and 70 wt % of treated CaCO₃ from the priorart or treated CaCO₃ made according to the process of the presentinvention.

TABLE 6 Masterbatch: LLDPE Dowlex 2035G at 30 wt % + 70 wt % of CaCO₃Filterpressure Test Filterpressure Test Pore size filter 14 μm 25 μm 70wt % CaCO₃ 0.68 n/a bar/g treated (invention) 70 wt % CaCO₃ 2.50 n/abar/g treated (prior art 1) 70 wt % CaCO₃ 6.69 1.07 bar/g treated (priorart 2) 70 wt % CaCO₃ 7.34 1.77 bar/g treated (prior art 3)

The CaCO₃ according to the present invention clearly shows itsbeneficial properties over the CaCO₃ of the prior art 1-3 when made intoa masterbatch. The pressure on the pore filter at 14 μm shows that theCaCO₃ of the prior art causes clogging of the filter due to baddispersed and/or coarse CaCO₃ particles, whereas the CaCO₃ according tothe present invention, causes no clogging and thus also no significantpressure build up at the pore size filter, thus nicely demonstrating theadvantageous properties, the improved dispersion of the CaCO₃ particlesin the polymer matrix.

Further to this, said filled LLDPE masterbatches were made into blownfilm by means known to the skilled person. Samples of the said blownfilms comprising the CaCO₃ according to the present invention andsamples of blown films comprising the prior art CaCO₃ are comparedhereafter in table 7. Different amounts of filled masterbatch were mixedwith a further LLDPE (Dowlex 5056G) and blown films were made from thesemixtures.

TABLE 7 Aquatrac Formulation of examples ppm g/cm³ 1 2 3 4 5 6 7 LLDPEDowlex 0.919 100.0 85.7 71.4 85.7 71.4 66.7 71.4 5056G 70% MB 484 1.73014.3 28.6 Invention 70% MB PA1 460 1.730 14.3 28.6 60% MB 1.540 33.3Invention 70% MB PA2 618 1.730 28.6 Weight of the kg 100.0 100.0 100.0100.0 100.0 100.0 100.0 mixture Density of the g/cm³ 0.92 0.99 1.06 0.991.06 1.06 1.06 mixture Universal tests Tensile strength ISO N/mm² 10.310.4 10.4 10.3 10.2 10.7 10.0 at yield, MD¹ 527 Tensile strength ISON/mm² 9.4 9.3 9.7 9.9 8.9 10.3 9.8 at yield, CD² 527 Elongation ISO %13.7 9.8 9.2 11.1 8.6 9.2 9.9 at yield, MD¹ 527 Elongation ISO % 9.5 8.06.9 8.1 6.5 6.8 7.4 at yield, CD² 527 Tensile strength ISO N/mm² 60.353.7 45.3 44.4 38.0 36.5 31.7 at break, MD¹ 527 Tensile strength ISON/mm² 55.1 45.1 35.7 33.2 29.5 35.2 25.1 at break, CD² 527 ElongationISO % 561 514 509 502 487 507 448 at break, MD¹ 527 Elongation ISO % 609581 558 519 526 570 488 at break, CD² 527 Elmendorf tear ISO cN 287 298362 328 391 461 393 propagation 6383/2 resistance, MD¹ Elmendorf tearISO cN 406 397 522 453 522 564 531 propagation 6383/2 resistance, CD²E-modulus, MD¹ ISO N/mm² 246 280 299 282 317 314 298 527 E-modulus, CD²ISO N/mm² 246 270 304 297 315 347 316 527 Opacity 13.4 16.6 20.9 15.718.7 20.6 18.4 Dart drop impact grams 441 609 561 453 348 621 219Thickness, MD¹ μm 23 20 21 24 23 23 24 Thickness, CD² μm 22 21 22 22 2222 23 ¹MD refers to machine direction, ²CD refers to cross direction.

70% MB Invention refer to 70 wt % of a masterbatch of 30 wt % LLDPEDowlex 2035G and 70 wt % of CaCO3 according to the present invention,wherein the treated CaCO₃ has a median particles size diameter d₅₀ of0.8 μm, a top cut of d₉₈ of 3 μm, and a BET specific surface area of 6m²/g.

70% of MA PA1 refers to 70 wt % of a masterbatch of 30 wt % LLDPE Dowlex2035 and 70 wt % of a ground surface treated CaCO₃ of the prior art,comprising an acrylic dispersing agent, wherein the surface treatingagent is stearic acid, and the CaCO₃ has a median particle size diameterd₅₀ of 1.6 μm and a top cut of d₉₈ of 6 μm.

70% MA PA2 refers to 70 wt % of a masterbatch of 30 wt % LLDPE Dowlex2035 and 70 wt % of a ground surface treated CaCO₃ of the prior art,comprising an acrylic dispersing agent, wherein the surface treatingagent is stearic acid, and the CaCO₃ has a median particle size diameterd₅₀ of 0.8 μm and a top cut of d₉₈ of 5 μm, and a BET specific surfacearea of 10 m²/g.

As can be seen from the inventive examples 2, 3 and 6 from table 7, thetensile strength at break as well as the dart drop impact aresignificantly improved, while at the same time the film thicknessreduced, compared to the comparative examples of the prior art 4, 5 and7. Example 1 being the unfilled LLDPE Dowlex 5056G.

It lies within the scope of the present invention that the LLDPEmentioned are not the only one and that other LLDPE polymers aresuitable as well to be used for producing a masterbatch comprising theCaCO₃ of the present invention.

Therefore, the masterbatch comprising the CaCO₃ of the present inventioncan be used not only in blown films, but also in the extrusion of pipes,tubes, or hoses, in sheet extrusion, in cast film for subsequentthermoforming, and other processed known to the skilled person.

Use in PP Masterbatch

Still another embodiment of the mineral matter according to the presentinvention is now presented. The mineral material of the presentinvention is made into a master-batch of a polyolefine. In particularthe mineral material of the present invention in treated form iscompounded into a polypropylene (PP). The PP is present in amounts ofabout 10 wt % to about 80 wt % and the treated mineral material of thepresent invention is present in amounts of about 90 wt % to about 20 wt%. Preferably the PP is present in amount of 20 wt % to about 50 wt %and the treated mineral material according to the present invention ispresent in amounts of 80 wt % to about 50 wt %. More preferably the PPis present in amounts of 25 wt % to about 45 wt % and the treatedmineral material according to the present invention is present inamounts of 85 wt % to about 60 wt %, most preferably the masterbatch iscomposed of 30 wt % to 40 wt % of the PP and of 70 wt % to about 60 wt %of the treated mineral material according to the present invention, andwherein the median particle diameter d₅₀ was determined on the untreatedmineral material and has a value from about 0.1 μm to about 1.5 μm,preferably from about 0.4 μm to about 1.1 μm, more preferably from about0.6 μm to about 0.9 μm, and most preferably of 0.8 μm, and wherein theBET/N2 specific surface area is measured on the untreated mineralmaterial and amounts from 4 m2/g to 15 m2/g, preferably from 6 m2/g to10 m2/g, more preferably from 7 m2/g to 8 m2/g.

Suitable PP materials are commercial products including, but are notlimited to: PPH 9099 homopolymer polypropylene having a melt flow rateof 25 g/10 min, available from Total Petrochemicals; PPH 10099homopolymer polypropylene having a melt flow rate of 35 g/10 min,available from Total Petrochemicals; Lumicene MR 2001 homopolymerpolypropylene having a melt flow rate of 25 g/10 min, available fromTotal Petrochemicals; Moplen HP462R polypropylene having a melt flowrate of 25 g/10 min, available from LyondellBasell; Moplen HP561Rpolypropylene having a melt flow rate of 34 g/10 min, available fromLyondellBasell; HG455FB homopolymer polypropylene having a melt flowrate of 27 g/10 min, available from Borealis.

The mineral material can be any natural or synthetic calcium carbonateor calcium carbonate comprising material selected from the groupcomprising marble, chalk, dolomite, calcite, limestone, magnesiumhydroxide, talc, gypsum, titanium oxide or mixtures thereof.

A filter pressure test was performed in order to determine the filterpressure value FPV of a PP masterbatch as described above and comparedto the FPV a master-batch comprising a mineral material of the priorart.

The filter pressure test as herein described provides for the FilterPressure Value, in the present case, of dispersed mineral material,tested with Borealis HF 136 MO, a polypropylene homopolymer with a MFRof 20 g/10 min. The Filter Pressure Value FPV is defined as the increaseof pressure per gram filler. This test is performed to determine thedispersion quality and/or presence of excessively coarse particles oragglomerates of mineral materials in a masterbatch. Low Filter PressureValues refers to a good dispersion and fine material, wherein highFilter Pressure Values refer to bad dispersion and coarse oragglomerated material.

The Filter Pressure test was performed on a commercially availableCollin Pressure Filter Test, Teach-Line FT-E20T-IS, according to thestandard EN 13900-5. Filter type used was 14 μm; extrusion was carriedout at 230° C.

The masterbatch which was tested was composed of 25 wt % of a PP, with aMFR 2.16 at 230° C. of 25 g/10 min.

Further to this, said filled PP masterbatches were used by meltextrusion processes to form fiber and filaments and continuous filamentnonwoven fabrics by means known to the skilled person.

In accordance with known technology such as the continuous filamentspinning for yarn or staple fiber, and nonwoven processes such asspunbond production and meltblown production, the fibers and filamentsare formed by extrusion of the molten polymer through small orifices. Ingeneral, the fibers or filaments thus formed are then drawn or elongatedto induce molecular orientation and affect crystallinity, resulting in areduction in diameter and an improvement in physical properties.

Spunmelt is a generic term describing the manufacturing of nonwoven webs(fabrics) directly from thermoplastic polymers. It encompasses 2processes (spunlaid and meltblown) and the combination of both.

In this process polymer granules are melted and molten polymer isextruded through a spinneret assembly which creates a plurality ofcontinuous polymeric filaments.

The filaments are then quenched and drawn, and collected to form anonwoven web. Some remaining temperature can cause filaments to adhereto one another, but this cannot be regarded as the principal method ofbonding. There are several methods available for forming the collectedweb of continuous filaments into a useful product by a bonding step,which includes, but is not be limited to calendaring, hydro-entangling,needling and/or bonding by means of chemicals or adhesives.

The spunlaid process (also known as spunbonded) has the advantage ofgiving nonwovens greater strength. Co-extrusion of second components isused in several spunlaid processes, usually to provide extra propertiesor bonding capabilities.

In meltblown web formation, low viscosity polymers are extruded into ahigh velocity airstream on leaving the spinneret. This scatters themelt, solidifies it and breaks it up into a fibrous web.

It is known to those skilled in the art to combine processes or thefabrics from different processes to produce composite fabrics whichpossess certain desirable characteristics. Examples of this arecombining spunbond and meltblown to produce a laminate fabric that isbest known as SMS, meant to represent two outer layers of spunbondfabric and an inner layer of meltblown fabric. Additionally either orboth of these processes may be combined in any arrangement with a staplefiber carding process or bonded fabrics resulting from a nonwoven staplefiber carding process. In such described laminate fabrics, the layersare generally at least partially consolidated by one of the bondingsteps listed above.

Processes are well known in the art, and are commercially available, forproducing spunbond fabric of polypropylene polymeric resin. The twotypical processes are known as the Lurgi process and the Reifenhä userprocess.

The Lurgi process is based on the extrusion of molten polymer throughspinneret orifices followed by the newly formed extruded filaments beingquenched with air and drawn by suction through Venturi tubes. Subsequentto formation, the filaments are disbursed on a conveyor belt to form anonwoven web.

The Reifenhä user process differs from the Lurgi process in that thequenching area for the filaments is sealed, and the quenched air streamis accelerated, thus inducing more effective entrainment of thefilaments into the air stream.

In the above-described systems, nonwoven fabrics are generally producedusing polypropylene resins having a melt flow index of about 25 to 40grams/10 minutes. A Lurgi line was used to produce polypropylenenonwovens. Extruder temperatures are between 230° and 250° C. The fourspin beams are equipped with melt pumps and spinnerets which contain 600orifices each with a diameter of 0.8 millimeters. The extruded filamentsare formed to a nonwoven web. The conveyor belt speed was adjusted to 20meters/minute and hydroentangling was used to bond the nonwoven web.Hydroentangling, also known as spunlacing, is a process which employshigh pressure water jets to entangle fibers in a loose web therebycreating a fabric held together by frictional forces between the saidfibers. The final bonded nonwoven web with a width of 100 cm has afabric weight of 385 g/m².

Samples of the said nonwoven fabrics comprising the CaCO₃ according tothe present invention and samples of nonwoven fabrics comprising theprior art CaCO₃ are compared hereafter in tables 8 and 9. Differentamounts of the filled master-batches were mixed with furtherpolypropylene (PP HF420FB, a homo-polypropylene with MFR 19 g/10 min.(230° C., 2.16 kg, ISO 1133) from Borealis) and nonwoven fabrics weremade from these mixtures.

Measuring Methods

If not otherwise indicated, the parameters mentioned in the presentinvention are measured according to the measuring methods describedbelow.

Measurements Done on Filament Samples

Titer or Linear density [dtex] may be measured according to EN ISO 2062and corresponds to the weight in grams of 10,000 m yarn. A sample of 25or 100 meters is wound up on a standard reel under a pretension of 0.5cN/tex and weighted on an analytical scale. The grams per 10,000 m yarnlength are then calculated.

Tenacity is calculated from the breaking force and the linear density,and expressed in centinewton per tex [cN/tex]. The test is carried outon a dynamometer with a constant stretching speed, applicable standardsfor this test are EN ISO 5079 and ASTM D 3822.

Breaking Force and Elongation at Break: The breaking force is the forceneeded to be applied on a yarn to make it break. It is expressed inNewton [N]. The elongation at break is the increase of the lengthproduced by stretching a yarn to its breaking point. It is expressed asa percentage [%] of its initial length. Tensile index is the product oftenacity [cN/tex] and the square root of the elongation at break [%].

Measurements Done on Nonwoven Samples

Fabric weight or mass per unit area [g/m²] is measured according to ENISO 9864. Tensile properties of geotextiles are measured according to ENISO 10319 using a wide-width strip with 200 mm width and 100 mm lengthon a tensile testing machine. Tensile strength [kN/m] and the elongationat maximum load [%] are measured in machine direction (MD) and in crossmachine direction (CD). The energy value according to EN ISO 10319 iscalculated by the tensile strength (MD+CD)/2.

Static puncture resistance (CBR test) in [kN] is measured according toEN ISO 12236. This method specifies the determination of the punctureresistance by measuring the force required to push a flat-ended plungerthrough geosynthetics.

TABLE 8 Formulation 1 2 3 4 5 Polypropylene 100 96 96 96 96 HF420FB 70%MB Invention 1 4 70% MB PA1 4 70% MB Invention2 4 70% MB PA2 4 TestsNorm Unit On Filaments Linear density dtex 8.46 8.64 9.3 8.59 TenacitycN/tex 26.9 26.0 24.2 24.3 Elongation % 217 211 206 207 Tensile index —395 377 347 349 On Nonwoven Fabric weight EN ISO 9864 g/m² 379 387 396393 Coefficient CBR EN ISO12236 N/g 8.4 8.3 7.7 8.0 Tensile Strength ENISO 12319 N/g 11.2 10.9 10.6 11.0 (MD + CD)/2 Elongation MD ¹ EN ISO12319 % 77 78 76 83 Elongation CD ² EN ISO 12319 % 98 105 92 99 ¹ MDrefers to machine direction, ² CD refers to cross direction.

TABLE 9 Formulation 1 2 3 4 5 Polypropylene 100 96 96 96 96 HF420FB 70%MB Invention 1 4 70% MB PA1 4 70% MB Invention2 4 70% MB PA2 4 TestsNorm Unit On Filaments Linear density dtex 9.7 9.6 9.9 10.1 TenacitycN/tex 22.6 21.2 20.5 21.7 Elongation % 260 235 248 234 Tensile index —364 325 323 332 On Nonwoven Fabric weight EN ISO 9864 g/m² 354 382 359378 Coefficient CBR EN ISO12236 N/g 6.8 6.9 6.9 7.7 CBR EN ISO12236 N2383 2632 2483 2899 Tensile Strength EN ISO 12319 N/g 10.3 9.2 9.5 9.1(MD + CD)/2 ¹ MD refers to machine direction, ² CD refers to crossdirection.

70% MB Invention1 refers to 70 wt % of a masterbatch of 28 wt % PPLumicene MR 2001 a metallocene homo-polypropylene with MFR 25 g/10 min.(230° C., 2.16 kg, ISO 1133) from Total Petrochemicals and 2 wt %Irgastab FS 301, processing and thermal stabilizer from BASF and 70 wt %of CaCO₃ according to the present invention, wherein the treated CaCO₃has a median particles size diameter d₅₀ of 0.8 μm, a top cut of d₉₈ of3 μm, and a BET specific surface area of 6 m²/g.

70% MB Invention2 refers to 70 wt % of a masterbatch of 28 wt % PPHF420FB, a homo-polypropylene with MFR 19 g/10 min. (230° C., 2.16 kg,ISO 1133) from Borealis and 2 wt % Irgastab FS 301, processing andthermal stabilizer from BASF and 70 wt % of CaCO₃ according to thepresent invention, wherein the treated CaCO₃ has a median particles sizediameter d₅₀ of 0.8 μm, a top cut of d₉₈ of 3 μm, and a BET specificsurface area of 6 m²/g.

70% of MA PA1 refers to 70 wt % of a masterbatch of 28 wt % PP LumiceneMR 2001 a metallocene homo-polypropylene with MFR 25 g/10 min. (230° C.,2.16 kg, ISO 1133) from Total Petrochemicals and 2 wt % Irgastab FS 301,processing and thermal stabilizer from BASF and 70 wt % of a wet groundsurface treated CaCO₃ of the prior art, and the CaCO₃ has a medianparticle size diameter d₅₀ of 1.7 μm and a top cut of d₉₈ of 6 μm.

70% of MA PA2 refers to 70 wt % of a masterbatch of 28 wt % PP LumiceneMR 2001 a metallocene homo-polypropylene with MFR 25 g/10 min. (230° C.,2.16 kg, ISO 1133) from Total Petrochemicals and 2 wt % Irgastab FS 301,processing and thermal stabilizer from BASF and 70 wt % of a wet groundsurface treated CaCO₃ of the prior art, and the CaCO₃ has a medianparticle size diameter d₅₀ of 1.7 μm and a top cut of d₉₈ of 6 μm.

As can be seen from the inventive example 2 from table 8, the tensileproperties, especially the tenacity and the tensile index aresignificantly improved compared to the comparative examples 3 and 5. Theinventive examples 2 and 4 from table 9 show the same improvementcompared to the comparative example 5. Example 1 being the unfilledpolypropylene PP HF420FB.

It lies within the scope of the present invention that thepolypropylenes mentioned are not the only one and that other PP polymersor PE polymers or a mix of PP and PE polymers are suitable as well to beused for producing a masterbatch comprising the CaCO₃ of the presentinvention.

The polypropylene masterbatch comprising the CaCO₃ according to thepresent invention can be used for the production of mono filaments,tapes, multifilaments. Such filaments can either be spundbond ormeltblown and be readily made in to non-woven such as listed here below.

-   -   Hygiene (baby diapers, feminine hygiene, adult incontinence,        nursing pads    -   Wipes (medical wipes, industrial wipes, household wipes)    -   Agro textiles (crop protection, capillary mats, greenhouse        shading, root, control, seed blankets)    -   Geotextiles (road/rail building, dam/canal lining, sewer liners,        soil stabilization, drainage, golf/sport surfaces, roofing,        insulation)    -   Medical (face masks, head wear, shoe covers, disposable        clothing, wound dressings, sterilisation aids)    -   Filtration (air filters, liquid filters, tea bags, coffee        filters)    -   Technical (cable wrapping, floppy disk liners)    -   Automotive (head liners, insulation door panels, air filters,        battery separators, floor coverings)    -   Upholstery (artificial leather)    -   Household (wall covering, table decoration, floor coverings)

Use in Concrete

Table 10, shows the use of the mineral material of the present inventionin different amounts in a standard concrete mixture compared with afiller of the prior art.

Sand SAN099 Cement CEM099 CaCO3 added mass mass Water/ Desig- (density2.65 g/ml) (density 3.1 g/ml) (density 2.7 g/ml) water additive airwater density Rc24h Rc28d binder nation g g wt % g g g g g g/ml Mpa Mparatio Ref 1750 525 0.0 0 157 0 1032 598 2.38 11.4 22.6 0.30 PA1 1655 52510.0 52.5 173 0 1085 623 2.35 13.8 22.5 0.33 PA1 1608 525 15.0 78.8 1810 1132 639 2.30 22.4 35.3 0.34 Ref 1750 525 0.0 0 157 0 1042 603 2.3711.6 21.8 0.30 IN1 1655 525 10.0 52.5 173 0 1117 634 2.31 17.4 33.3 0.33IN1 1608 525 15.0 78.8 181 0 1194 683 2.34 37.8 72.5 0.34

In a specific embodiment the CaCO₃ of the present invention is anon-treated natural ground CaCO₃ having a medium particle size diameterof d₅₀ of 0.8 μm a top cut d₉₈ of 3 μm and a BET surface area of 6 m²/gwhich was mixed with a standard sand SAN099 as defined in Standard EN196-1, Cement CEM I 42.5N (CEM099), with different amount of CaCO₃filler, wherein 0 wt %, 10 wt % and 15 wt % of CaCO₃ fillers are basedon the weight of the cement binder. The concrete mixture furthercomprised water in amounts adapted to achieve the same workability. Thepresent examples were prepared without further additives. The concretemixture have the same volume of 986 ml. Said volume being calculated as:[mass sand]/[density sand]+[mass cement]/[density cement]+[volumewater].

Of course, other additives well known in the art could be added to theconcrete mix without departing from the scope of the present invention.For example one could add water reducing agents, retarding agents,accelerating agents, super-plasticizers, corrosion inhibiting agents,pigments, surfactants, air entraining agents and others well known tothe skilled person.

The method of preparing the concrete mixture according to table 10 andevaluation of the results is made according to the description of the USpatent application US 2012/0227632 of the same applicant.

PA1 refers to a non-treated natural ground CaCO₃ of the prior art havinga medium particle size diameter of d₅₀ of 1.4 μm a top cut d₉₈ of 5 μmand a BET surface area of 5.5 m²/g.

IN1 refers to a non-treated natural ground CaCO3 of the presentinvention, wherein the CaCO3 has medium particle size diameter of d₅₀ of0.8 μm a top cut d₉₈ of 3 μm and a BET surface area of 6 m²/g.

Ref refers to a concrete mixture reference without CaCO₃ at all.

Rc refers to compression resistance also known as compressive strengthmeasurements after 24 hrs and 28 days of maturation of the concretesamples, which were carried out according to the method as described inUS 2012/0227632 of the same applicant and EN 196-1. With the CaCO₃ ofthe present inventions the stabilities compared to the prior art wereincreased by about 25% at 10 wt % of filler, and about 270% at 15 wt %of filler after 24 hrs. After 28 days, the stability was increased byabout 50% at 10 wt % of filler and by about 100% at 15 wt % of fillercompared to the filler of the prior art.

The invention claimed is:
 1. A process for preparing a ground mineralmaterial in the absence of a dispersing agent consisting of the stepsof: a) wet grinding mineral material in at least one grinding step in anaqueous suspension or slurry in the absence of a dispersing agent untilthe mineral material has a weight median particle diameter d₅₀ from 1.1μm to 1.5 μm, wherein the mineral material is selected from the groupconsisting of marble, chalk, dolomite, calcite, limestone, magnesiumhydroxide, talc, gypsum, titanium oxide, and any mixture thereof; b)up-concentrating or dewatering the aqueous suspension or slurry of stepa) in the absence of a dispersing agent to achieve a solids content ofbetween 50% and 70%; c) drying the aqueous suspension or slurry of stepa) or b) to achieve a solid content of 99.8%, wherein no dispersingagent is present in the mineral material so obtained; and d) optionallysurface treating the mineral material obtained in step c) with at leastone aliphatic carboxylic acid; and e) optionally de-agglomerating themineral material after step d), wherein the calcium carbonate aftergrinding in step a) and before optional treatment in step d) has aBET/N₂ specific area of from 3 m²/g to 13 m²/g, wherein the mineralmaterial obtained in step c) has a top cut d₉₈ of 1.8 μm-5.9 μm.
 2. Theprocess according to claim 1, wherein the mineral material is wet groundin step a) until the mineral material has a weight median particlediameter d₅₀ of 1.1 μm.
 3. The process according to claim 1, wherein themineral material is wet ground in step a) until the mineral material hasa weight median particle diameter d₅₀ of 1.5 μm.
 4. The processaccording to claim 1, wherein in step b) the aqueous suspension orslurry is up-concentrated or dewatered to achieve a solids content ofbetween 55% and 65%.
 5. The process according to claim 1, wherein instep b) the aqueous suspension or slurry is up-concentrated or dewateredto achieve a solids content of 60%.
 6. The process according to claim 1,further comprising a de-agglomeration step e) after step d).
 7. Theprocess according to claim 1, wherein the mineral material is wet groundin step a) at a solids content of from 10 wt % to 40 wt %.
 8. Theprocess according to claim 1, wherein the mineral material is wet groundin step a) at a solids content of from 20 wt % to 30 wt %, and step b)uses up-concentrating which is carried out by centrifugation.
 9. Theprocess according to claim 1, wherein the mineral material is selectedfrom the group consisting of marble, chalk, dolomite, calcite,limestone, and any mixture thereof.
 10. The process according to claim1, wherein the up-concentrating of step b) is carried out by mechanicaland/or thermal means.
 11. The process according to claim 1, wherein thedrying in step c) is carried out by atomizing, spray drying, drying in arotational oven, drying in a pond, jet-drying, fluid bed drying, freezedrying, fluidized spray drying, or fountain nozzle drying.
 12. Theprocess according to claim 1, wherein the drying in step c) is carriedout by spray drying.
 13. The process according to claim 1, wherein stepd) takes place and the at least one aliphatic carboxylic acid isselected from the group consisting of butanoic acid, pentanoic acid,hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoicacid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid,pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid,nonadecanoic acid, arachidic acid, heneicosylic acid, behenic acid,lignoceric acid, and any mixture thereof.
 14. The process according toclaim 1, wherein the mineral matter in step a) is calcium carbonate.